1. Technical Field
The invention relates generally to a container and more specifically to a container such as a capsule used to deliver dosages of pharmaceuticals, medicines, vitamins, etc. to an individual.
2. Related Art
Standard containers for pharmaceuticals or other powdered, granular, or liquid substances, so-called telescope-type capsules, include a tubular-shaped or cylindrically-shaped first part, namely the cap part, which is closed on one end and open on the other end. A tightly fitting second part of similar shape, but of smaller diameter, can be telescopically inserted into the cap part, the second part being referred to as the main part or body part. FIG. 1 shows an illustrative conventional capsule 100 including a cap 110 and a body 140. Cap 110 includes an open end 112 and a closed end 114. Similarly, body 140 includes an open end 142 and a closed end 144. Open end 142 of body 140 is of a slightly smaller diameter than open end 112 of cap 110 such that body 140 may be partially inserted into cap 110. A separation of cap 110 and body 140 is prevented by friction and/or various modifications of an exterior surface of body 140 and/or an opposed inner surface of cap 110. For example, U.S. Pat. No. 5,769,267 to Duynslager et al., which is hereby incorporated by reference, discloses a two-piece telescoping capsule having corresponding connection units on the cap part and body as well as protrusions on an inner surface of the cap part to increase friction between the cap part and the body.
Usually, the containers are supplied to a filling apparatus in a “prelock” condition in which the body part is telescoped only partially into the cap. The two parts are separated in the filling machine and then fully closed after the filling operation.
In addition to various locking mechanisms intended to secure the various parts of a multi-part capsule after filling, the parts may alternatively or additionally be sealed by various methods. Generally, such sealing includes the spraying with a liquid or dipping of the capsule parts in a liquid. Such liquid may itself provide adhesive and/or sealing properties. Alternatively, such liquid may result in the partial dissolution or disintegration of portions of the capsule parts, whereby the capsule parts are fused or sealed upon evaporation of the liquid. Illustrative liquid sealing methods and solutions are disclosed in U.S. Pat. No. 4,893,721 to Bodenmann et al., which is hereby incorporated by reference. The particular liquid chosen will depend, in part, upon the composition of the capsule parts, but may include, for example, water or an alcohol.
Capsules may be constructed from a variety of film-forming agents such as gelatin, hydroxypropylmethylcellulose (HPMC), pullulan, etc. A number of defects have been observed in known devices, particularly deformations and microcracks in capsule walls. Deformations may result from a thinning and/or weakening of a capsule wall due to an excess of sealing fluid, which necessarily at least partially dissolves or disintegrates a material of the capsule wall.
Microcracks generally take the form of small breaks or discontinuities and almost always appear near a locking structure cap, i.e., portions of the cap and body providing a friction fit to prevent opening of the capsule. Microcracks result from stresses upon the capsule parts combined with a locally low loss on drying (LOD), i.e., low moisture content, and thus brittleness. Stresses may result, for example, from an internal capsule pressure, e.g., from the closing and/or heating of the capsule, or stresses placed upon the capsule parts themselves due to the force required to insert the capsule body into the capsule cap. The locally low LOD or brittleness may result, for example, from the presence of an alcohol vapor, which acts as a dehumidifier, in a gap between the cap and the body or from the drying of the capsule material, also attributable to an alcohol in the sealing fluid.
It has been observed that pullulan is particularly susceptible to these defects. Pullulan capsules experience higher than normal rates of failure after a sealing process, due, at least in part, to the fact that pullulan dissolves in room temperature water. Gelatin forms a phase intermediate between a solid and a liquid upon application of water, wherein the chain structure of the gelatin remains intact. In contrast, upon the application of water, pullulan transitions from a solid to a liquid. As a result, the strength of pullulan is lost locally near the sealing area. In this case, deformations may be common, resulting in the bending, swelling, or rupturing of capsules. Examples of failure include improper sealing, deformation, etc. As a result, current capsule designs are not well suited to allow for the liquid sealing of a pullulan-based multi-piece capsule.
There is, therefore, a need in the art for a multi-piece capsule design that can be sealed, such as with a conventional alcohol/water spray, and is not susceptible to deformation or failure of the capsule due to a liquid sealing process.